Method of manual door operation of vertically movable doors



June 17, 1 R. H. SOMMERS ET AL 2,600,441

METHOD OF MANUAL DOOR OPERATION OF VERTICALLY MOVABLE DOORS Filed Oct.29, 194? 3 Sheets-Sheet 1 r E O (D E 0 JNVENTORS R0552 H. SUM/V5196 BYARTHUR 14 F/SA/V/f June 17, 1952 R. H. SOMMERS ET AL METHOD OF MANUALDOOR OPERATION OF VERTICALLY MOVABLE DOORS Filed Oct. 29, 1947 5Sheets-Sheet 2 mmvrow ROBf/Pf so/ww/es y ART/90A W. FHA NA A TTOR/VEYPatented June 17, 1952 METHOD OF MANUAL DOOR OPERATION OF VERTICALLYMOVABLE DOORS Robert H. Summers, Waukesha, and Arthur W. Frank,Wauwatosa, Wis., assignors to Hevi Duty Electric Company, Milwaukee,Wis, a corporation of Wisconsin Application October 29, 1947, Serial No.782,818

Claims.

1 Our invention relates broadly to heat treating apparatus and moreparticularly to an improved method and structure of door closuremechanism for heat treatment apparatus.

One of the objects of our invention is to provide an arrangement ofclosure mechanism for heat treatment apparatus in which the full weightof the door of the closure mechanism may be used to effect closure ofthe opening of the heat treatment apparatus.

Another object of our invention is to provide a door closure mechanismfor heat treatment apparatus in which the mass of the door is effectiveagainst cam-like or inclined door jamb members arranged to force thedoor into sealed relation to the opening in the heat treatment apparatusunder control of door lifting and lowering mechanism.

Still another object of our invention is to provide a construction ofreversible pawl mechanism for controlling the position of the associateddoor mechanism under manual control.

A further object of our invention is to provide a construction ofgravitationally actuated pawl and sprocket mechanism for selectivelypositioning a counterweighted door closure of a heat treatment chamber.

Other and further objects of our invention reside with novel arrangementof closure mechanism for heat treatment apparatus as set forth morefully in the specification hereinafter following by reference to theaccompanying drawings in which Fig. 1 is a front view of a heattreatment apparatus equipped with a door operating mechanism of ourinvention; Fig. 2 is a side elevational view of a heat treatmentapparatus showing the door operating mechanism of our inventionassociated therewith; Fig. 3 is a fragmentary end elevational view ofthe door control mechanism employed in the system of our inventionillustrating the reversible pawl in position for lowering the heattreatment appa ratus door; Fig. 4 is a view similar to the view shown inFig. 3 but illustrating the position of the reversible pawl for raisingthe heat treatment apparatus door; Fig. 5 is an enlarged fragmentaryfront elevational view of the door control mechanism illustrated inFigs. 3 and 4 but showing a portion of the sprocket wheel broken awayand illustrated in section; Fig. 6 is a fragmentary vertical sectionalview through the door control mechanism with the pawl and certain of theassociated parts shown in elevation; Fig. '7 is an elevational view ofthe reversible pawl; Fig. 8 is a horizontal sectional view takensubstantially on line 3-5 of Fig. '7 Fig. 9 is an end view of the pawlshown in Figs. 7 and 8; Fig. 10 is a vertical sectional view takensubstantially on line lt-lfi of Fig. 7; Fig. 11 is a horizontalsectional view taken through the gravitationally weighted shiftable armassociated with the pawl. meohanism, the View being taken substantiallyon line ll-l l of Fig. 12; and Fig. 12 is an elevational view of thegravitationally weighted shiftable arm shown in Fig. 11.

In heat treating operations where the operator is' required to raise orlower a furnace door manually, several disadvantages exist in mechanismheretofore available. Chief among these disadvantages has been the factthat the door, being counterbalanced, and not having a means ofrelieving the counterweight, did not remain closed as tightly as desiredso as to exclude undesirable atmosphere or retain atmosphere used withinthe heating chamber. This can be readily understood as doors often weightwo. or three hundred pounds and must be counterweighted so that theywill operate freely with very little manual effort. Vibration within abuilding or carelessness in adjusting the mechanism'or in operationtends to allow the door to creep open a trifle, thus causing the door'toleak at its juncture with the furnace opening.

Makeshift methods are often employed to correct this condition such asplacing additional weights on the furnace door and wedging or clampingit against the furnace chamber opening. These various methods all add todifficulties in operation requiring extra labor.

The importance of maintaining the proper type and amount of atmospherein a furnace chamber can best be illustrated by the fact that it isoften necessary to spend as much or more on equipment to produceatmosphere than it does for the furnace itself, thus, to waste itthrough a leaky door is inefiicient and expensive.

Another effect of a leak at the chamber opening is that the draft of airentering the furnace not only contaminates the atmosphere, but producesVariations in temperature which are detrimental to furnace operations.

Another disadvantage has been that the operator was required to use bothhands to perform the operation of raising or lowering the door becauseof the necessity of having to engage or disengage a pawl or other devicefrom the chain sprocket while holding the door raising cranl: at thesame time. This did not allow the operator to work efficiently andrequired that he lay down his tongs or other tool so as to free bothhands before he could open or close the door. In operations requiringthe insertion and removal of work from the furnace in rapid succession,such as in the treatment of high-speed steels, delay is quiteobjectionable as it hinders the operator at a time when he should behandling material with the utmost speed.

Our invention is directed to mechanism that is incorporated into thedoor lift equipment which provides a simple means forthe operator tolift the weight of the counterweight in such manner that the full weightof the door in the door jamb is used to effect an improved seal betweenthe door and the furnace chamber. Likewise this same mechanism enables afurnace operator to raise or lower the door and then hold it at anydesired height through the use of the mechanism described thus leavingboth hands free to handle tongs or other equipment to insert or removework from the furnace. This latter advantage is especially useful in theheat treatment of high speed steels where speed in operation isessential to inserting or removing work from the furnace in order that aminimum amount of contamination of the atmosphere within the furnacewill result and that the steel can be handled between operations in asshort a time as possible to prevent surface deterioration.

Other advantages are apparent; the mechanism can be set to perform thedesired function of holding the door at the proper level, or to assistin lifting the counterweights, in advance of the time the operator isrequired to perform the operation. Thus if it is necessary to hold thedoor open at a certain height, the operator will set the mechanism inposition while the door or cover is closed and at a later time be freeto raise the door and hold it at the desired level without having tooperate a mechanism other than the door operating crank.

One preferred way of accomplishing the object of this invention will beunderstood by detailed reference to the accompanying drawings in whichthe door I is shown in closed position against furnace 2 and resting onlugs, either solid or roller type, 3 in the inclined door jambs 4.Chains 5 extend upward from the door I over sprockets 6 and down tocounterweights I. Sprocket B is attached to a. shaft 8 on which is alsomounted a sprocket 9 driven by an endless chain which, in turn, passesaround sprocket II which can be turned by operating crank l2 attached toshaft 14 on which operating crank I2 is secured.

We provide in addition to the mechanism described a special pawl l whichincorporates two projections [5a and [5b to engage the sprocket llwelded to a horizontal bar I50 which is pivoted at a point l6equidistance from each end, thus allowing the pawl Hi to be raised orlowered at either end. Adjacent to this pawl l5 and mounted on the samepivot I6 is a weight I! carried by an arm l8 which extends upwards andover the pawl l5 and can be moved from side to side so as to shift theweight to either side of the pawl l5 to engage either of the proiectionsl5a; or 15b in the sprocket H as desired by the operator. As eitherprojection Pia or l5b engages the sprocket II at some distance past thecenter line it will be understood that the pawl prevents the sprocket IIfrom being reversed, and allows it to travel freely in one directionuntil stopped by the operator or other mechanical limitations. The armI8 is apertured at 18a and registers with aperture We both of which arealigned and which fit over the pivot l6. Pivot I6 is in the form of astud bolt secured to bracket l9 fastened to the structural support 20 offurnace 2. In actual use the operator of the equipment would follow theprocedure outlined hereinafter:

To raise the door I the weight I! would be moved to the position shownin Fig. 4 where arm I 8 has moved weight into a position rocking bar I50in a counterclockwise direction, which would cause the pawl l5 to rotateto disengage projection l5b from the sprocket ll upon release by theoperator. The operator would then depress handle I2 slightly, allowingthe pawl IE to release and the weight I! to shift the projection l5a ofpawl l5 into engagement with sprocket II in a position for raising thedoor I. The door I can then be raised by the process of turning thecrank 12 until the desired height is reached. At this point, a slightreversal of the sprocket H would engage the projection [5a of pawl l5and lock the door at the desired height. Then the operator would movearm I8 in a clockwise direction as shown in Fig. 3 which moves theweight I! in the opposite direction, abutting weight ll against bar I5cin a direction to shift projection 151) into engagement with sprocket Hin the position shown in Fig. 3 where the mechanism is ready to closethe door I.

In closing the door I, the operator would again slightly reverse thesprocket l l releasing the projection I5b of pawl 15 which woulddisengage due to the fact that the weight 11 had been shifted, and wouldlower the door I to a closed position.

In order that the operator may more effectively seal the door by takingthe load of the counterweight '1 off it, he would continue to turn thecrank l2 until the chains 5 supporting the door I showed evidence ofslack. This extra slight turn would usually mean that the pawl [5 wouldengage the sprocket one or two teeth past where it would have stopped ifno additional pressure had been exerted. By using the full weight of thedoor I, the inclined jambs 4 would more effectively force the door Iagainst the front of the furnace 2, thus creating a better seal, theadvantages of which were indicated hereinbefore.

The reversible pawl mechanism 15 provides for the unidirectional controlof the lifting or lowering mechanism and insures the stopping of thedoor selectively at the desired position. Reversal of the pawl mechanismI5 is performed very simply and quickly by angular displacement of thearm H3 in the desired direction as explained in connection with Figs. 3and 4. The sealing of the door with respect to the opening of the heattreatment apparatus is made very effective by the forcing of the doorinto sealing relation with the sides of the opening in the heattreatment apparatus by the coaction of the lugs 3 extending in oppositedirections from the door into the inclined guideways formed by the doorjambs A. The fact that the inclines in the door jambs are directedtoward the opening in the heat treatment apparatus insure the movementof the door toward the opening in the heat treatment apparatu forestablishing sealing relation therewith.

While we have described our invention in one of its preferredembodiments we realize that modifications and changes may be made in themechanism we have illustrated and we desire that it be understood thatno limitations upon our invention are intended other than may be imposedby the scope of the appended claims.

What we claim and desire to secure by Letters Patent of the UnitedStates is as follows:

1. Door operating mechanism including a vertically movable door,vertically arranged guideways for controlling the movement of said doorin a vertical direction, counterweighted means for balancing thevertical movement of said door and control means for moving said door toa selected position, said control means including a reversible crank,achain and sprocket mechanism operated by said reversible crank with saidchain operatively associated with said counterweighted means, areversible pawl pivotally mounted adjacent said sprocket mechanism,substantially coplanar with said chain mechanism.

and having a pair of angularly directed teeth members having overalldimensional limits of less than the distance between the paths of travelof said chain mechanism and operative to engage the sprocket teeth ofsaid sprocket mechanism at a position remote from the center thereof anda weighted lever pivotally mounted on the same center with said pawl andoperative to be shifted to either of two limiting positions engagingsaid paWl for gravitationally maintaining one of the teeth members ofsaid pawl in toothby-tooth engagement with the sprocket teeth of saidsprocket mechanism for unidirectionally controlling the movement of thedoor to a selected position.

2. Door operating mechanism including a vertically movable door,vertically arranged guideways for controlling the movement of said doorin a vertical direction, counterweighted means for balancing thevertical movement of said door, and control means for moving said doorto a selected position, said control means including a reversible crank,a chain and sprocket mechanism with said chain operatively associatedwith said counterweighted means, a reversible pawl pivotally mountedadjacent said sprocket mechanism comprising a plate member having a pair.of normally projecting spaced diverging teeth thereon directed towardand alternately engageable with the teeth of said sprocket mechanism andoperative in a plane substantially coplanar with a plane through saidchain mechanism, and means angularly shiftable about the pivotal centerof said reversible pawl for gravitationally maintaining one of the teethof said pawl in tooth-by-tooth engagement with the sprocket teeth ofsaid sprocket mechanism for unidirectionally controlling the movement ofthe door to a selected position.

3. Door operating mechanism including a vertically movable door,vertically arranged guideways for controlling the movement of said doorin a vertical direction, counterweighted means for balancing thevertical movement of said door, and control means for moving said doorto a selected position, said control means including a chain andsprocket mechanism with said chain operatively associated with saidcounterweighted means, a reversible pawl pivotally mounted adjacent saidsprocket mechanism comprising a plate member having a pair of normallyprojecting spaced diverging teeth thereon directed toward andalternately engageable with the teeth of said sprocket mechanism, alever arm concentrically mounted with respect to the pivotal mounting ofsaid pawl and a weight carried by the end of said lever arm, said weightbeing angularly shiftable into selective engagement with the rear ofeach of the teeth on said plate member in either of the limits ofangular movement thereof for gravitationally maintaining one of theteeth of said pawl in tooth-bytooth engagement with the sprocket teethof said sprocket mechanism for unidirectionally controlling the movementof the door to a selected position.

4. Door operating mechanism including a vertically movable door,vertically arranged guideways for controlling the movement of said doorin a vertical direction, counterweighted means for balancing thevertical movement of said door and control means for moving said door toa selected position, said control means including a chain and sprocketmechanism with said chain operatively associated with saidcounterweighted means, a reversible pawl pivotally mounted adjacent saidsprocket mechanism comprising a plate member having a pair of normallyprojecting spaced diverging teeth thereon directed toward andalternately engageable with the teeth of said sprocket mechanism, saidplate member and said teeth having a total overall linear dimension thatis less than the direction between the paths of travel of said chainmechanism, and a lever arm pivoted adjacent said sprocket mechanism andhaving a weighted mass projecting substantially normal thereto and oversaid plate member for engaging said plate member in either of thelimiting positions thereof substantially within the limits of the lineardimension of said plate member for gravitationally maintaining one ofthe teeth of said pawl in tooth-by-tooth engagement with the sprocketteeth of said sprocket mechanism for unidirectionally controlling themovement of the door to a selected position.

5. Apparatus for controlling the vertical movement of a balanced doorcomprising a chain and sprocket, a reversible crank connected with saidsprocket, said chain extending around said sprocket in substantiallyparallel paths, a pivotally mounted bar located between the paths oftravel of the chain, said bar carrying a tooth at each end thereofdisposed in a plane substantially normal to the plane of said bar, eachtooth being alternately engageable, at the limits of movement of thebar, with the teeth of said sprocket, a lever arm concentrically mountedwith respect to the pivotal mounting of said bar, and a weight carriedby the end of said lever arm and projecting over said bar andselectively engageable therewith adjacent opposite ends of the bar formaintaining one or the other of the teeth in engagement with saidsprocket for latching the sprocket and the chain engaged therewith in aselected position subject to release by a reverse movement of saidcrank, said bar and the teeth thereon and said lever arm all beingdisposed between the paths of travel oftthe chain and substantiallycoplanar therewi h.

ROBERT I-I. SOMMERS. ARTHUR W. FRANK.

REFERENCES CITED The following references are of record in the file ofthis patent:

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